linux-kernel - Re: [PATCH 2/2] KVM: LAPIC: Guarantee the timer is in tsc-deadline mode when setting

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Message-ID: <20200804211943.GC31916@linux.intel.com>
Date:   Tue, 4 Aug 2020 14:19:43 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Wanpeng Li <kernellwp@...il.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH 2/2] KVM: LAPIC: Guarantee the timer is in tsc-deadline
 mode when setting

On Tue, Aug 04, 2020 at 02:10:48PM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@...cent.com>
> 
> Check apic_lvtt_tscdeadline() mode directly instead of apic_lvtt_oneshot()
> and apic_lvtt_period() to guarantee the timer is in tsc-deadline mode when
> wrmsr MSR_IA32_TSCDEADLINE.
> 
> Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
> ---
>  arch/x86/kvm/lapic.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index d89ab48..7b11fa8 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -2193,8 +2193,8 @@ void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data)
>  {
>  	struct kvm_lapic *apic = vcpu->arch.apic;
>  
> -	if (!kvm_apic_present(vcpu) || apic_lvtt_oneshot(apic) ||
> -			apic_lvtt_period(apic))
> +	if (!kvm_apic_present(vcpu) ||
> +		!apic_lvtt_tscdeadline(apic))

Definitely prefer to fix the indentation here since both lines are touched
anyways.

>  		return;
>  
>  	hrtimer_cancel(&apic->lapic_timer.timer);
> -- 
> 2.7.4
>